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Understanding Protein Quality: PDCAAS, Bioavailability & Amino Acids

6 min read

Why Is Not All Protein Equal?

Not all protein is equal because amount alone says little about the quality of a protein. Three factors are decisive: the amino acid profile, bioavailability and the scientific quality index. Anyone looking to optimise their protein intake should understand these factors.

Which Protein Sources Provide the Most Protein?

SourceProteinFibreAmino Acids
bunaroba Protein Powder54g12gComplete*
Whey protein powder80g0gComplete
Chicken breast31g0gComplete
Salmon20g0gComplete
Eggs13g0gComplete
Greek yoghurt10g0gComplete
Lentils (cooked)9g8gLimited**
Tofu8g0.3gLimited**

*Pea + hemp protein complement each other to form a complete amino acid profile **Limited in methionine - combination with grains recommended

What Do PDCAAS and DIAAS Say About Protein Quality?

PDCAAS and DIAAS are the two most important scientific indices for measuring protein quality. PDCAAS (Protein Digestibility Corrected Amino Acid Score) and DIAAS (Digestible Indispensable Amino Acid Score) measure how well the body can utilise the protein. Higher = better.

Protein SourcePDCAASDIAASRating
Egg (whole)1.00113Very high
Chicken breast1.00108Excellent
Pea protein (concentrate)0.8964-82Good
Hemp protein0.46-0.5143-54Limited (lysine)

Pea + hemp complement each other: pea provides lysine, hemp adds methionine. Combined, they form a complete amino acid profile.

bunaroba combines pea and hemp protein. This creates complementary amino acid profiles while additionally providing magnesium and iron.

How Much Protein Does the Body Actually Absorb?

Depending on the source, the biological value ranges from about 64 to 104. It shows how much of the absorbed protein the body can convert into its own protein (egg = 100 as reference, Hoffman and Falvo, 2004).

Protein SourceBiological valueSignificance
Egg (whole)100Reference standard
Beef80Very good
Soy74Good

Why Are Essential Amino Acids So Important?

Essential amino acids are crucial because the body cannot produce them on its own and they must be obtained from food. The body cannot produce 9 amino acids on its own - they must be obtained from food. For muscle building, BCAAs (leucine, isoleucine, valine) are particularly important.

Amino AcidFunctionBest Sources
LeucineDescribed as a trigger of muscle protein synthesisEgg, chicken, pea protein, beef
IsoleucineEnergy supply for musclesEgg, salmon, beef
ValineEnergy supply to the musclesDairy products, peanuts
LysineCollagen formation, calcium absorptionMeat, fish, pea protein
MethionineMetabolism, sulphur donorEggs, fish, hemp protein
ThreonineCollagen, elastinMeat, dairy products
TryptophanSerotonin precursor, sleepTurkey, seeds, tofu
PhenylalanineNeurotransmittersMeat, fish
HistidineHistamine productionMeat, fish, hemp seeds

Leucine is particularly important: around 1 to 3 g per meal is recommended (ISSN, 2017). Pea protein provides well above the leucine requirement (Gorissen, 2018).

Why Combine Pea + Hemp?

Pea protein is rich in lysine and leucine but limited in methionine. Hemp protein complements with methionine and additionally brings fibre, plus per 30 g of hemp protein 64% of the reference intake for magnesium, 30% for iron and 33% for zinc. Combined, they perfectly complement each other to form a complete amino acid profile with valuable micronutrients.

This complementarity is not coincidental but a well-established principle of nutritional science: different plant protein sources compensate for each other’s limiting amino acids.

Conclusion

Protein quality is at least as important as quantity. Plant-based proteins come close to animal sources in their amino acid composition when intelligently combined. The combination of pea and hemp protein unites a complete amino acid profile with valuable micronutrients.

bunaroba Protein Powder contains 12 g of dietary fibre per 100 g. Whey contains 0 g.

Learn more about optimal protein requirements by activity level and goal in our article How Much Protein You Really Need. Or calculate your individual needs directly with the Protein Calculator.


Sources:

  • Rutherfurd SM et al. (2015). Protein Digestibility-Corrected Amino Acid Scores and Digestible Indispensable Amino Acid Scores. The Journal of Nutrition, 145(2), 372-379. DOI: 10.3945/jn.114.195438
  • FAO (2013). Dietary protein quality evaluation in human nutrition. FAO Food and Nutrition Paper 92. ISBN 978-92-5-107417-6. fao.org
  • Gorissen SH et al. (2018). Protein content and amino acid composition of commercially available plant-based protein isolates. Amino Acids. DOI: 10.1007/s00726-018-2640-5
  • House JD et al. (2010). Evaluating the quality of protein from hemp seed products through the use of the protein digestibility-corrected amino acid score method. Journal of Agricultural and Food Chemistry. DOI: 10.1021/jf102636b
  • Hoffman JR, Falvo MJ (2004). Protein - Which is Best? Journal of Sports Science & Medicine, 3(3), 118-130. jssm.org
  • Jäger R et al. (2017). International Society of Sports Nutrition Position Stand: protein and exercise. Journal of the International Society of Sports Nutrition. DOI: 10.1186/s12970-017-0177-8
  • Herreman L et al. (2020). Comprehensive overview of the quality of plant- and animal-sourced proteins based on the digestible indispensable amino acid score. Food Science & Nutrition, 8(10), 5379-5391. DOI: 10.1002/fsn3.1809
  • Nosworthy MG et al. (2023). The in vivo and in vitro protein quality of three hemp protein sources. Food Science & Nutrition, 11(11), 7264-7270. DOI: 10.1002/fsn3.3652
  • Hevia-Larraín V et al. (2021). High-Protein Plant-Based Diet Versus a Protein-Matched Omnivorous Diet to Support Resistance Training Adaptations. Sports Medicine. DOI: 10.1007/s40279-021-01434-9
  • Burd NA, Beals JW, Martinez IG, Salvador AF, Skinner SK (2019). Food-First Approach to Enhance the Regulation of Post-exercise Skeletal Muscle Protein Synthesis and Remodeling. Sports Medicine, 49(Suppl 1), 59-68. DOI: 10.1007/s40279-018-1009-y

Frequently Asked Questions

What do PDCAAS and DIAAS mean?
PDCAAS (Protein Digestibility Corrected Amino Acid Score) and DIAAS (Digestible Indispensable Amino Acid Score) measure how well the body can utilise a protein. Egg reaches 1.00 (PDCAAS) and 113 (DIAAS). In combination, plant proteins come close to animal protein in their amino acid composition.
Is plant-based protein powder worse than whey?
Not necessarily. The combination of different plant sources (e.g. pea + hemp) forms a complete amino acid profile. One study found no differences in muscle building with the same high protein intake (around 1.6 g/kg) (Hevia-Larraín et al., 2021).
Why are different protein sources combined?
Pea protein is rich in lysine but low in methionine. Hemp protein complements with methionine and additionally provides magnesium and iron. Combined, they form a complete amino acid profile that comes close to animal protein.

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Disclaimer

The information on this page is provided for general informational and educational purposes only. It does not constitute medical advice, diagnosis or treatment recommendations and is not a substitute for professional medical consultation. Dietary supplements are not a substitute for a balanced and varied diet and a healthy lifestyle. If you have health concerns, pre-existing conditions, are pregnant, breastfeeding or taking medication, please consult a physician before use. Bunaroba AG assumes no liability for decisions made based on this content. Despite careful research, errors cannot be excluded.

Editorial responsibility for this article: Roger Giese. How we use AI tools is set out under Use of AI.